We are applying for funds to support the purchase of instrumentation, necessary to serve the flow cytometry needs of the research community at Tufts University School of Medicine (TUSM) and Tufts-New England Medical Center (T-NEMC). The facility has been in existence for 17 years and has been run for the last 6 years by Mr. Allen Parmelee, a skilled and respected operator, under the direct supervision of the P.I. and the Core Advisory Committee. Under their direction the facility has grown, become highly successful and maintained financial stability through competitive pricing and Departmental support. 85% of facility time is dedicated to the NIH funded work of the Core User Group. We are now asking for an LSR II (BD Biosciences) analytical machine. This instrument will double our analytical capacity, while providing access to a powerful range of techniques not currently available to us, including the measurement of intracellular calcium in cells expressing GFP variants, using Indo-1 (355nm laser); the tracking of cell cycle, viability, and proliferation, using Hoechst or DAPI (355nm laser); the analysis of protein expression, using CFP (405nm laser); the measurement of molecular association at the nanometer scale, using CFP-to-YFP FRET (405nm laser) and any analysis requiring 5 or more colors. The cost efficiency and high standards of our facility have encouraged use to the point where the facility (one FACSCalibur and one, soon to be two, MoFLos) is now over-extended. In addition, new faculty hiring, combined with growing interest in flow applications throughout TUSM and, recently, T-NEMC has increased the size of our NIH funded Core User Group from 6 to 17. This renders the acquisition of a new LSR II essential, if we are to meet the flow cytometry needs, both in time and available technology, for the community of NIH funded researchers at TUSM and T-NEMC. [unreadable] [unreadable]